After 22 months of testing, NOAA started using a sophisticated new short term weather forecast model.  The Rapid Refresh Model (RAP) for short, will improve predictions of quickly developing severe weather situations such as thunderstorms, winter storms, and aviation hazards like turbulence.  It replaces an older model called Rapid Update Cycle (RUC).

RAP was developed by NOAA’s Earth System Research Lab in Boulder, CO and the National Centers for Environmental Predicton in Camp Springs, MD.  It updates every hour producing a fresh forecasting extending 18 hours over most of North America.  The U.S. is the only country in the world to routinely update a weather forecast model every 1 hour with the latest observations from ground and satellite based sensors, along with radar, ships, and aircraft.

Forecast skill has improved using the RAP model for most variables including wind and precipitation.  For example the RAP did a better job of showing where a large area of extreme rainfall would occur last June over the middle of the country.  Aviation interests in Alaska are seeing improvement to flying safety using this model.  This is especially important to that state because there are numerous sections of Alaska only accessible by airplane.

You can learn more about the RAP model and other forecasting issues from the following link.  http://www.noaanews.noaa.gov/stories2012/20120501_rapmodel.html

Posted under forecast, Science, Severe Weather, Technology, Weather NEws

Before I get into the severe thunderstorm outlook for upcoming days, I thought you might be interested in seeing how widespread this recent cold snap has been.  Freeze Warnings are in effect Wednesday night all the way down to Tennessee and North Carolina.  A good dozen states or more are covered (the area in blue on the map).

Weather Advisories Wednesday Night

Rain is likely Friday around here with a small chance of a thunderstorm Saturday.  However it looks like the threat of severe storms with large hail, high winds, and tornadoes will stay in the Plains.

The convective outlook from the Storm Prediction Center for Friday shows the risk area mostly in Kansas, Oklahoma, into far northern Texas.  That part of the country will be in a flow of warm and muggy air with dew points climbing into the 60s.  A low pressure system emerging from the Rockies into the Plains along with strong jet stream winds will aid the formation of violent weather.

Severe Thunderstorm Risk Area for Friday

Severe Thunderstorm Outlook for Saturday

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Finally, I want to bring up a sneaky weather feature that occasionally helps to develop or enhance precipitation and storms.  It is called gravity wave.  It is a rapidly moving ripple of energy with alternating up and down air motions.  It normally shows up on satellite imagery as a striped area of clouds with clear breaks between them.  Here is an example in the image below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This gravity wave train ended up producing a thunderstorm with softball size hail in parts of Texas.  We really have to watch them carefully, especially where they might intersect an existing front or boundary.  That’s usually where the big action is.  You can learn much more about this fascinating case and gravity waves in general by checking out this link from the Storm Prediction Center.  http://www.spc.noaa.gov/coolimg/gwavecb.htm

Posted under forecast, Freeze, Severe Weather, Storms

For the first time in four years, the Northern Plains will not experience major to record spring snowmelt flooding.  Of course the reason being is that there was very little snowpack in that part of the country throughout the winter.  Most of the major winter storms either missed that area, or it was warm enough that the snow melted off and on over the winter months.  The record warmth in March took care of the rest of any remaining snow pack in the Upper Midwest as well.  This is certainly great news for residents in Fargo and Grand Forks along the Red River as well as folks along the Mississippi River.

There is also a lower than normal risk of spring flooding in the southwest quadrant of the county as well as an area from Florida to parts of Virginia.  Only a few spots in Louisiana, Mississippi, Kentucky, and southern Indiana, and southeast Illinois have an above normal chance of spring floods according to NOAA.

The bad side of lower than normal spring flood risk in the Northern Plains and Midwest is the fact that this usually means the ground will dry out sooner than normal.  Thus there is a somewhat increased chance of growing season drought, unless frequent rains start to show up.

You can read NOAA’s full spring hydrologic assessment at this link.  http://www.nws.noaa.gov/hic/nho/

Posted under Flooding, forecast, Natural Disasters, Seasonal Items, Storms, Weather NEws

I just crunched the numbers and this March turned out as extraordinary as we thought it might several weeks ago.  In fact it was the warmest on record in Wausau and much of the Midwest region for that matter.  Accurate temperature record generally date back to around 1880 in our area. 

In Wausau, the average high in March 2012 was 55.3 degrees which is 15.8 degrees above normal.  The average low was 36.3 degrees which is also 15.8 degrees above normal.  The mean temperature for the month was 45.8 degrees.  This eclipses March of 1910 for the record warmest mean when we had 43.3 degrees.  I can’t tell you how rare it is to break the all time temperature record for a month by almost 3 degrees.  Usually if you were to do it, you would squeak by by a degree.  Of course what really put us over the top was the middle portion of the month when record  high temperatures were established on 11 of 13 days in Wausau.

As far as precipitation goes, it was dry.  We had 1.13″ of rain or melted snow in Wausau which is .63″ below normal.  We picked up just 1.6″ of snow, which is 8.4″ below normal.  The lack of moisture did not stop fruit trees and certain flowers from blooming out a good month early.

WHY IT STAYED SO COOL SATURDAY?

We were hoping temperatures might climb up into the lower 60s Saturday but a stubborn layer of low level moisture, stratus clouds, and fog refused to move out.  We had a temperature inversion in place several thousand feet aloft that helped trap the moisture and clouds.  Plus we had southeast winds which this time of the year tend to drag and stable, cool, moist marine air off the cool Great Lakes.  That did not help the situation either.    Below you will see the surface observation map around 4 p.m. Saturday.   The red numbers on the map were the current temperatures.  There was an amazing spread from the lower 40s in Wisconsin to near 90 degrees in eastern Nebraska and 80s in South Dakota.  Of course they had the sunshine out and a wind direction off the Plains helping to drive the warm air aloft down to the surface.  Hopefully we will tap into some of that warmth and sunshine Sunday.

Posted under forecast, Monthly Recap, Records, Seasonal Items

While we could have a rumble of thunder around here Monday night into early Tuesday, it appears the main threat of strong or severe thunderstorms will remain from far southern Wisconsin down through the Kansas area Tuesday afternoon.  That region is under a slight risk classification from the Storm Prediction Center.  The reason is that warm, and more humid air will be surging north ahead of a cold front.  Temperatures there could reach the 70s making the air rather unstable.  The cold front would be the trigger to lift the air and initiate the storms.  Strong winds in the atmosphere and turning wind direction in height could allow several of the cells to become supercells with rotation.  Thus a few tornadoes are possible, especially from west-central Illinois into Missouri.  Otherwise damaging winds over 50 mph and hail to 1.5″ diameter will be possible as far north as Janesville, WI.

On a different note, I did a talk at the Simek Library in Medford Saturday regarding weather technology and other topics.  One question from the audience came up regarding the Fujita scale.  That scale has been around for numerous decades as it was developed by Dr. Theodore Fujita in the 1960s and 70s.  It ranks tornado strength on a scale from F0 to F5, with F5 being the strongest.   Research in the past 10 years regarding how winds damage buildings has allowed an upgrade to the scale.   It is now called the Enhanced Fujita scale or EF scale.  You can read all about the scale and how it’s applied by reading this article from the Storm Prediction Center.  http://www.spc.noaa.gov/efscale/

Posted under forecast, Severe Weather, Spring, Storms, Tornadoes

I suppose if you had to guess what the spring might hold for us in Wisconsin, you would say warmer than normal conditions.  That is what the Climate Prediction Center’s updated outlook for April calls for too.  They project most of the eastern two-thirds of the nation to have above normal temperatures.  They pinpoint the greatest likelihood of above normal temperatures around the Southern Plains.  They are predicting an increased chance of cooler than normal temperatures in the Pacific Northwest.

April Temperature Outlook from CPC

As far as precipitation goes,  the Climate Prediction Center indicates that above normal amounts are possible from Michigan south to Tennessee basically.    They think that drier than normal conditions are more likely in places like Arizona, New Mexico, Colorado and in a strip from southern Texas over to Florida and South Carolina.  The CPC has Wisconsin in an area of equal chances of below, normal, and above precipitation.  So there is no strong signal either way from the models and ocean-atmospheric patterns.  We normally get around 3″ of moisture in April in our region.

April Precipitation Outlook from CPC

At this time, there is still a weak La Nina pattern ongoing in the tropical Pacific Ocean.  However it is projected to dissipate completely by May.  One thing we’ll have to keep an eye on around Wisconsin with the warmer than normal weather is the possibility of earlier than normal severe thunderstorm outbreaks.  Usually severe weather season doesn’t hit high gear until mid May to early June around here.  That’s normally when the warm, humid air necessary for severe storms and tornadoes makes a more regular appearance to our area as the jet streams migrate northward.  However this year, it appears those conditions will come together about a month early perhaps.

Posted under CPC Outlook, ENSO Update, forecast, Seasonal Items, Spring

I would like to delve a little more into the science and weather news of the day but the impending Winter storm has taken up most of my time and I suspect it is on everyone’s mind anyway, so today’s blog will once again be about the potential snowfall, and rainfall, and sleet-fall (if that is a word).

So what has changed since yesterday’s analysis? I have dropped the snow totals slightly and shifted the heaviest potential snow a little north of the Wausau metro area. As you can see from the graphic, I am now forecasting 3 to 6 inches of heavy wet snow (mixed with rain and sleet at times) for Marathon county and the highway 29 corridor. The line for the heavier snow (and not as much rain or sleet, is likely to be just north of the Wausau metro area and on up into the Northwoods. For areas south of Marathon county, there is a good chance there will be more rain and sleet than snow. Right now I am looking at 1 to 3 inches of snow in the southern areas late tonight, followed by some heavier rain around daybreak.

Snow Potential

With the rain and milder temps developing in the morning, the roads might not be too bad south of Marathon county.

A couple key things to remember with this storm is that there could be some rather extreme differences in snow totals in the transition zone between rain/sleet and snow – that means Marathon county. As I was mentioning yesterday, in the transition zone there can be a 9 inch snow report just a few miles away from a 1 inch report. There could also be some thundersnow at times that can really enhance the snowfall. Thundersnow can produce snowfall rates of 4 or 5 inches per hour. This is also possible in the transition zone.

The second thing to remember is that the heaviest rain, sleet, and snow will occur quite early in the morning, through about 7 or 8 am for central Wisconsin. For the rest of the day on Wednesday, the weather will likely be mild (a few degrees above freezing) with only a little drizzle and patchy light snow. The only locations that could pick up an additional 2 to 4 inches of snow later in the morning through early afternoon are in the northwoods.

NAM snow forecast

For a comparison to our StormTrack9 snow potential graphic, I have also included one computer model projection of snowfall. This particular computer model (the NAM) calculates a maximum of 19.7 inches of snow in the northwestern corner of the state and generally 10 to 15 inches of snow for the northwoods. It also shows a sharp cut-off of where there will be a lot of snow and where there will be none. It does have a known bias of over-estimating precipitation, but it seems fairly close this time around.

There will be another storm system moving into the upper Midwest on Friday, but at this time it looks like the highest potential for accumulating snow will be confined to the far southeastern part of the area, in cities such as Shawano, Waupaca, and Wautoma.

Have a nice Tuesday! Meteorologist Justin Loew.

Posted under forecast, Severe Weather, Winter Weather

By now you are probably aware of the significant amount of wet snow and sleet expected in our region Tuesday night into Wednesday.  Since we are approaching spring and we’ve had some bare ground off and on through the winter, your next question is probably….when will it melt???

Typically it melts fairly fast this time of the year.   Often times warm air sneaks in within a few days of a big snowfall this time of the year.  Plus even without a warm push of air, the sun angle is getting so high it readily melts snow even when the actually air temperatures are below freezing.  According to some weather models we may very well have a fairly strong warm up next week.  In fact the charts below show air aloft a few thousand feet running about +6 degrees C by Monday-Tuesday March 5th-6th as a brisk southwest wind blows in.  If some sunshine accompanied that, high temperatures would likely jump well into the 40s. 

A front and low pressure system are also projected to slide through the middle of the country around Wednesday and Thursday, March 7th-8th.  The GFS model below actually shows a good quarter inch of rain potential.  That would certainly accelerate the melting process.

GFS model rainfall projection for Thursday, March 8th

So the bottom line is, the snow won’t last all that long.  Oh we could very well get more snow off and on through March but the trend on the thermometer is definitely going to be up.  So I project the ground should be mostly bare again by the 10th or 15th of March.  In the meantime, be careful out there Tuesday evening through Wednesday with the mess on the roads.

Posted under forecast, Spring

The big news continues to be the active jet stream pattern and storm potential for our area. I mentioned last week how we should not get too much Spring Fever yet, because Winter is not over and that there were several potential storms on the horizon. We got hit with a couple inches of snow on Monday of last week, then the second and third storm in this pattern missed. One headed into southern Wisconsin and northern Illinois last Thursday night and produced several inches of snow. The next headed into far northern Wisconsin (near Lake Superior and the UP of Michigan) and produced 2 to 3 inches on Sunday.

The fourth storm in this active weather pattern is what I will focus on today. It will be cruising through the upper Midwest Tuesday evening and Wednesday. The National Weather Service has already issued a WINTER STORM WATCH for the entire Newsline 9 viewing area for this time period. It doesn’t look like this storm will be the most “energetic” or strongest storm we have had in the last couple of years, but it will have a high amount of moisture so the potential for heavy precipitation will still exist.

Snow Potential Tuesday Night & Wednesday

As of now, I am forecasting 8 to 12 inches of snow for areas around Clark, Marathon, and Shawano counties on up to around highway 8. Further north of highway 8, the snow should be a little less. South of Marathon county, it looks like 4 to 8 inches of snow. South of Wisconsin Rapids and Stevens Point, it might only be a trace up to 4 inches. The heaviest snow with this storm system will likely be in parts of central Minnesota and western Wisconsin. Over toward the Twin Cities, Eau Claire, and Rice Lake, there might be 15 or more inches of snow.

So what are the question marks that remain? Given that the storm is less than 36 hours away, there is less chance that it will completely change course and miss our area like the last two. There is a chance that more rain and sleet could mix in with the snow and thus keep snow totals more in the 4 to 8 inch range and not much more. There will likely also be a sharp cut-off between areas with little accumulation, in the far south, and a lot of accumulation farther north. In the past with this type of late Winter/early Spring storm I have seen a trace of snow fall in Stevens Point with close to 10 inches in Wausau on the same day. There could be such a sharp cut-off this time around as well. As far as the 8 to 12 inches accumulation, it looks like the lighter amounts (around 8 inches) will be east in the area, such as around Antigo, Wittenberg, and Tigerton, and the heavier amounts (closer to 12 inches) will be farther west in areas such as Medford, Withee, and Thorp. The record snowfall in Wausau on Wednesday is only 4.5 inches so we could end up setting a new record.

The storm will wind down on Wednesday afternoon and we will have a break in the action for Thursday, then another storm could hit on Friday. If it tracks over Wisconsin, we could be dealing with another several inches of rain, sleet, and snow. Be sure to check the blog, our weather page, twitter, and our facebook pages (news and weather) to stay informed about the storminess this week.

Have a good Monday! Meteorologist Justin Loew.

Posted under forecast, Winter Weather

The latest long range monthly outlooks have been released by the Climate Prediction Center (CPC) and if you are hoping for an early Spring you might be in luck. I say might because looking ahead months in advance is still a very in-exact science. The March outlook for Wisconsin indicates a significant chance of above normal temperatures across Wisconsin and most of the Great Lakes region. As a bonus, there is also a greater than normal chance of above normal precipitation. I am always happy if we head into the growing season with some added moisture. It helps everything turn green and start growing vigorously right away.

CPC March Temp Trend

Now just remember, as you are reading this and thinking about a potential mild March, don’t forget that the rest of the month of February is looking rather Winter-like. We have to get through the next couple of weeks before we will see whether or not the CPC forecast is correct. Also remember that above normal precipitation in March could mean either rain or snow. If we end up with a couple of big storms dumping several inches of snow, it might not seem like an early Spring, even if the majority of the days in March are above normal.

CPC March Precip Trend

As far as the longer term goes, the three month average of March-April-May is also predicted to have a chance of above normal temperatures in our part of the country. Otherwise, all other periods in the forecast indicate EQ or “equal chances” of above or below normal temps and precipitation. So basically, after a possibly mild March, the computer models can’t discern any major trends through the Summer.

Now an update on the current Wintry pattern referenced above. Light snow will continue off-and-on for the rest of today and might accumulate an inch or so. On Thursday another storm moving through the upper Midwest has the potential to produce 2 or 3 inches of snow but current charts indicate it might track through southern Wisconsin and not bring a whole lot of snow to Marathon county and further north. The third storm of the week will be developing later Sunday into Monday morning and has the potential to create several inches of snow. It is still too early to say where in the state the heaviest snow will fall.

Have a good Tuesday! Meteorologist Justin Loew.

Posted under CPC Outlook, forecast